The reason for the 5/16 drops on 3/16 laterals is because during the freeze - thaw cycle and the temperature drops the tree develops a negative pressure. That causes the tree to pull sap back into the tree. The shuttling of sap back and forth in the drop, spout and tap hole contributes to bacteria growth. This pulling of the sap back in the tree is more evident with 3/16 drops.
First introduced to making maple syrup in 1969
Making syrup every year since 1979
3 x 10 oil fired
Revolution syrup and max flue pan
Almost 1300 taps total with 900 on high vacuum
Bought first Marcland drawoff in 1997, still going strong.